NIST 800-171 3.1.1: Limit System Access to Authorized Users and Devices
Access control is the foundational security control that determines who and what can interact with your systems. NIST 800-171 3.1.1 requires you to limit system access to authorized users, processes acting on their behalf, and approved devices—preventing unauthorized access before it becomes a breach.
What this means
This control requires organizations to implement technical and administrative mechanisms that prevent unauthorized individuals, processes, and devices from accessing systems and data. This includes user authentication, role-based access policies, device management, and session controls. The goal is ensuring that only explicitly authorized entities can interact with your infrastructure.
How to comply
- 1.Define and document authorized users, processes, and devices with specific access rights and business justifications
- 2.Implement authentication mechanisms (passwords, MFA, certificates) to verify user identity before granting access
- 3.Deploy role-based access control (RBAC) or attribute-based access control (ABAC) to enforce least-privilege principles
- 4.Monitor and approve all system access requests through a formal change control process
- 5.Maintain and regularly audit access control lists (ACLs) to remove inactive users and outdated device entries
- 6.Restrict device access through hardware inventory management, device registration, and network controls
- 7.Configure session timeouts and automatic logoff to minimize exposure from unattended systems
- 8.Log all access attempts and maintain audit trails for accountability and forensic analysis
Evidence auditors look for
- Access control policy documents listing authorized users, roles, and device classifications
- Proof of MFA implementation and enrollment records for all user accounts
- Role definitions mapped to job functions with documented approval chains
- Device inventory and registration logs showing approved hardware
- Access control list (ACL) exports from systems, firewalls, and applications
- User access audit reports showing periodic reviews and access removal actions
- Session timeout configuration screenshots from systems and applications
- Access logs and authentication failure reports demonstrating monitoring and detection
- Onboarding and offboarding procedures documenting access provisioning and deprovisioning
Frequently asked questions
When will FAQs be available?
The FAQ for this control is currently being prepared.
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